1. Technical Field of the Invention
The present invention relates to a control system and a communication system capable of being properly used to control a digital mixer or the like.
2. Description of the Related Art
Conventionally, a serial bus (i.e., an I2C bus) for enabling a plurality of devices to communicate with each other via two signal lines has been well known to those skilled in the art. A specific bus (i.e., an E-bus) formed by applying the I2C bus to data communication between internal devices (e.g., a keyboard, a panel operator, an indicator, and a sound source, etc.) contained in an electronic musical instrument has been disclosed in Japanese Patent Laid-open Publication No. 2002-251183 and corresponding U.S. Pat. No. 6,700,050. A plurality of addresses from 1 to 127 are assigned to individual devices for use in the I2C bus, respectively. Therefore, a maximum of 127 devices can be theoretically connected to the I2C bus.
However, in fact, if the number of I2C devices is increased, a buffer-amplifier called a repeater should be inserted into several points of the I2C bus. Therefore, the number of repeaters for use in an apparatus composed of a plurality of devices is also increased, resulting in increased costs of production. Specifically, the digital mixer includes more numbers of operators and indicators. than those of the electronic musical instruments, such that it has a disadvantage in that it must unavoidably increase the number of devices on the I2C bus.
Each device connected to the I2C bus requires a bus interface for connection to the bus. In order to transmit data from the bus interface to other devices, the device requires a specific function for designating individual addresses of source and destination devices. For example, the bus interface is more complicated than a serial communication interface such as an RS232C.